我有一个问题：
我想在核心数据模型中添加值与实体之间的关系，并在视图中使用pickersView显示这些值。
我创建了一个示例，试图了解如何实现实体之间的关系，但现在我处于待机状态......我不知道如何在我的模型中使用mutableSetValueForKey，valueforkey，setvalue（_：forkey）。在我的例子中，设备或卡片链接到上面的项目。
我的coreData模型：3个实体：用户，设备和卡 用户 - 设备（nn）：n个设备到n个用户 设备 - 卡（1n）：1个设备可以有多个卡，但一个卡仅用于一个专用设备
见模型图片：
要填充，我有一个包含多个字段的视图，Pickers，buttons：
Usertexfield +添加按钮添加新用户
用户的选择器（显示/sélect用户）+ devicetextfield +添加按钮以向用户添加新设备
设备的选择器（显示/sélect设备）+ cardtextfield +添加按钮以将新卡添加到设备
Picker of cards（显示/sélect卡）
删除设备按钮以删除设备
删除卡片按钮以删除卡
我还希望能够在选择时修改设备或卡（非制作）
问题 ： 如何创建/修改/删除与用户关联的设备（如何在fetchrequest中实现这两个实体之间的关系？
这是我的代码（根本没有完成...）：请参阅addDeviceButton函数（如果可能的话还要添加addCardButton）
// createRelationshipsViewController.swift
// testcoredatarelationships
//
// Created by jIOP on 23/03/2016.
// Copyright © 2016. All rights reserved.
//
import UIKit
import CoreData
class createRelationshipsViewController: UIViewController, UIPickerViewDelegate, UIPickerViewDataSource {
// User
@IBOutlet weak var pickerUser: UIPickerView!
@IBOutlet weak var userNameTextField: UITextField!
@IBOutlet weak var boutonAddUser: UIButton!
// Device
@IBOutlet weak var pickerDevice : UIPickerView!
@IBOutlet weak var deviceNameTextField: UITextField!
@IBOutlet weak var boutonAddDevice: UIButton!
@IBOutlet weak var deleteActivite: UIButton!
//Card
@IBOutlet weak var pickerCard : UIPickerView!
@IBOutlet weak var carteNameTextField: UITextField!
@IBOutlet weak var boutonAddcard: UIButton!
@IBOutlet weak var deleteCard: UIButton!
//Actions
var tabpickerUser=[]
var tabpickerDevice=[]
var tabpickerCard=[]
override func viewDidLoad() {
super.viewDidLoad()
// init PickerView User only -others can't be at this time
let MOC = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
let fetchRequest = NSFetchRequest(entityName: "User")
var requestError: NSError?
/* And exécute the fetch request on the context */
usersInCD = (try! MOC.executeFetchRequest(fetchRequest)) as! [User]
// usersInCD is a list of Users
// tbd --> if nil picker is empty else init tabpickerUser with usersInCD.Name.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
@IBAction func addUserBoutonAction(sender: AnyObject) {
let MOCUser = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
let newUser = NSEntityDescription.insertNewObjectForEntityForName("User",inManagedObjectContext: MOCUser) as! User
newUser.userId = NSUUID().UUIDString
newUser.userName = userNameTextField.text // new user textfield
var savingError: NSError?
do {
try MOCUser.save()
print("New User created")
} catch let error1 as NSError {
savingError = error1
if let error = savingError
{
print("Failed to populate the database User. Error = \(error)")
}
// Update UserPicker --> Tbd
}
@IBAction func addDeviceBoutonAction(sender: AnyObject) {
let MOCDevice = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
// How to get userId from PickerView
// How to create a new device attached to this userId (predicate, mutableSetValueForKey, other ...)
let newDevice = NSEntityDescription.insertNewObjectForEntityForName("Device",inManagedObjectContext: MOCDevice) as! Device
newDevice.deviceId = NSUUID().UUIDString
newDevice.deviceName = deviceNameTextField.text
var savingError: NSError?
do {
try MOCDevice.save()
print("New device created")
} catch let error1 as NSError {
savingError = error1
if let error = savingError
{
print("Failed to populate the database Device. Error = \(error)")
}
}
@IBAction func addCardBoutonAction(sender: AnyObject) {
// same PB but with n--1 relationships between Device and Cards
// A card is associated to 1 device only / one device car have several cards
// usage of mutableSetValueForKey ?
}
@IBAction func deleteDeviceBoutonAction(sender: AnyObject) {
// How to delete device (device) --> device will delete the card ?
}
@IBAction func deleteCardBoutonAction(sender: AnyObject) {
// How to delete card, link to a device
}
/////////////////////////// Picker managment
func numberOfComponentsInPickerView(pickerView:UIPickerView) -> Int {
return 1
}
func pickerView(pickerView: UIPickerView,numberOfRowsInComponent component:Int) -> Int {
switch pickerView.tag {
case 1:
return tabpickerUser.count
case 2:
return tabpickerDevice.count
case 3:
return tabpickerCard.count
default:
print("Something else")
}
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
switch pickerView.tag {
case 1:
return tabpickerUser[row] as! String
case 2:
return tabpickerDevice[row]as! String
case 3:
return tabpickerCard[row]as! String
default:
print("Something else")
}
}
// Here add pickerView functions to update pickers views when user, device, card is added or remove.
// not done ...
/* Init pickerView Device and pickerView Card (how to do it ?)
Init pickerView Device when user is selected in UserpickerView
let MOC = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
// predicate to match UserId in Entity Device ?? how to do it using the relationships ????
//let predicate = NSPredicate(format: "userId == %@", tabpickerUser[row].userId!) ???????
fetchRequest.predicate = predicate
var requestError: NSError?
/* And execute the fetch request on the context */
Devices = (try! MOC.executeFetchRequest(fetchRequest)) as! [Device]
*/
/* Init pickerViewCard when Device is selected in DevicepickerView
let MOC = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext
let fetchRequest = NSFetchRequest(entityName: "Card")
var requestError: NSError?
// And execute the fetch request on the context
Cards = (try! MOC.executeFetchRequest(fetchRequest)) as! [Card]
*/
}